1. Field of the Invention
This invention relates to rotary devices of the axial vane type, particularly the class of devices where volume change occurs between relatively close vanes and cam surfaces on each side of the rotor and where the vanes translate axially relative to the rotational axis of the rotor.
2. Description of Related Art
Many different types of rotary engines have been suggested in the past and have been covered by a large number of patents. Only a relatively small number of these have been thoroughly tested. Many rotary engines are appealing on paper, but practical difficulties arise when prototypes are constructed.
The best known rotary engine is the Wankel engine which is in volume production in Mazda automobiles. Even this engine has had considerable difficulties with proper sealing of the rotors, although such problems have been largely overcome. However, the engine is not particularly efficient and high fuel consumption is a characteristic of vehicles using this technology.
Another type of rotary engine is referred to herein as the "axial vane type". This type of engine has a cylindrical rotor located within a cylindrical chamber in a stator. A plurality of blade-like vanes extend slidably through the rotor, parallel to the axis of rotation. There are undulating cam surfaces on each side of the rotor. High portions of the cam surface on one side align with low portions of the cam surface on the other side such that the vanes are caused to reciprocate back and forth in the axial direction as the rotor rotates.
One such engine is found, for example, in U.S. Pat. No. 4,401,070 by James Lawrence McCann. This type of engine compresses gases forwardly of each vane in the direction of rotation as the rotor rotates. The compression occurs as the vane moves from a low cam surface, relatively distant from the rotor, to a high cam surface relatively close the rotor. After the gases are compressed, they must be transferred to the rearward side of each vane prior to combustion so that the ignited gases will propel the rotor forwards.
The need for transferring the compressed gases is removed in a variation of this type of rotary engine such as found in Polish Patent No. 38112 to Czyzewski. In this case, the gases are compressed between adjacent vanes which are angularly spaced-apart much closer than in the McCann engine. The gases are compressed as each pair of adjacent vanes moves towards a high cam area. Expansion of the ignited gases is permitted, and the propulsion force created, as the vanes continue to move past the high cam area to a relatively low cam area after ignition.
This type of rotary engine offers many potential advantages including high efficiency, simple construction and light weight. However, while the theoretical possibility of such an engine has been suggested in the past, many practical difficulties have inhibited development of such engines beyond the stage of a working prototype. For example, some earlier patents do not disclose any practical system of seals between the rotor, vanes and stator. In addition, relatively high loads can occur on the tips of the vanes which can cause premature wear.
Accordingly it is an object of the invention to provide an improved axial vane rotary device which overcomes the disadvantages associated with earlier engines of the type. It is another object of the invention to provide an axial vane rotary device with reduced loading on the side edges of the vanes where they ride on the cam surfaces of this stator.
It is a further object of the invention to provide an improved axial vane rotary device with a positive, efficient and durable sealing system.
It is a still further object of the invention to provide an improved axial vane rotary device which is practical to produce, relatively low in cost and durable.